Liquid crystal display device with touch panel

ABSTRACT

A liquid crystal display device is provided in which a touch panel and a liquid crystal display panel are placed under a front window. A touch-panel flexible wiring substrate is connected to the touch panel, and a main flexible wiring substrate is connected to the liquid crystal display panel. The main flexible wiring substrate includes a touch-panel control IC and a touch-panel electronic component group to control the touch panel. The touch-panel flexible wiring substrate includes only lines. In this configuration, there is only one flexible wiring substrate, or the main flexible wiring substrate, on which the electronic components are mounted. As a result, the production cost of the liquid crystal display device as a whole can be reduced.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/814,583, filed on Jun. 14, 2010. Further, this application claimspriority from Japanese Patent Application JP 2009-144126 filed on Jun.17, 2009, the entire contents of which are hereby incorporated byreference into this application.

FIELD OF THE INVENTION

The present invention relates to a liquid crystal display device, andmore particularly to a small display device having a touch panel usedfor mobile phones or other electronic devices.

BACKGROUND OF THE INVENTION

A liquid crystal display device includes a TFT substrate and a colorfilter substrate. The TFT substrate is configured such that pixelelectrodes, thin film transistors (TFTs), and the like, are arranged ina matrix form. The color filter substrate is disposed opposite to theTFT substrate, in which color filters, and the like, are formed atlocations corresponding to the pixel electrodes of the TFT substrate. Aliquid crystal is interposed between the TFT substrate and the colorfilter substrate. Then, an image is formed by controlling thetransmittance of light of the liquid crystal molecules for each pixel.

The liquid crystal display device can be made small and thin, and isused in a wide range of applications such as mobile phones or otherelectronic devices. In recent years, various types of applications havebeen added to the mobile phone. Also, the input device is expected tohave a function allowing finger input through a touch panel, in additionto the conventional key-button operation. In this case, a touch panel isattached on the side of the color filter substrate of the liquid crystaldisplay panel.

There is a strong demand not only for reducing the overall size of theliquid crystal display device as a set, but also reducing the thicknessof the liquid crystal display panel, while the size of the screenremains unchanged. In order to meet the demand for a thin liquid crystaldisplay panel, a liquid crystal display panel is produced, and then theoutside of the liquid crystal display panel is polished to a desiredthickness. The liquid crystal display panel is formed by the TFTsubstrate having pixel electrodes, thin film transistors (TFTs), and thelike, and by the color filter substrate having color filters. The twosubstrates constituting the liquid crystal display panel are glasssubstrates that are standardized, for example, to a thickness of 0.5 mmor 0.7 mm. It is difficult to obtain such standardized glass substratesfrom the market. In addition, very thin glass substrate has a problemrelating to mechanical strength and bending in the production process,leading to a reduction in the production yield. For this reason, theliquid crystal display panel is formed by the standardized glasssubstrates, and then the outside of the liquid crystal display panel ispolished to a desired thickness.

The reduction of the thickness of the liquid crystal display panel posesa problem of the mechanical strength. When a mechanical stress isapplied to the display surface of the liquid crystal display panel,there is a risk that the liquid crystal display panel will be destroyed.The situation is the same with the liquid crystal display panel on whichthe touch panel is placed, due to the small thickness of the touchpanel.

In order to prevent the liquid crystal display panel from beingdestroyed by an external force, a front window of resin or glass isattached to the screen side of the liquid crystal display panel. In thiscase, an air layer is present between the liquid crystal display paneland the touch panel, or between the touch panel and the front window.The transmittance of the light from the backlight is reduced by thereflection from the interface in this area.

In order to prevent this, JP-A No. 83491/2008 describes a configurationin which an adhesive layer or an anti-reflection coating is formedbetween the liquid crystal display panel and the touch panel, or betweenthe touch panel and the front window. JP-A No. 83491/2008 also describesa configuration in which a main flexible wiring substrate is attached tothe liquid crystal display panel in order to connect the liquid crystaldisplay panel to an external circuit, and a touch-panel flexible wiringsubstrate is attached to the touch panel in order to connect the touchpanel to the external circuit. In JP-A No. 83491/2008, the touch panelis of a capacitance type and can function as a touch panel with thefront window thereon.

In the capacitance-type touch panel, various operations are possible.However, a touch-panel control IC and touch-panel electronic componentsare necessary for the touch panel to perform such various operations. Inthe past, the touch-panel control IC and the touch-panel electroniccomponents have been provided in the touch-panel flexible wiringsubstrate.

FIG. 11 is a top view of a conventional liquid crystal display devicehaving a front window 200 and a touch panel. In FIG. 11, the frontwindow 200 is shown in the top. The touch panel and the liquid crystaldisplay panel are hidden behind the front window 200, so that they donot appear in FIG. 11. In FIG. 11, a touch-panel flexible wiringsubstrate 50 is connected to the touch panel, and a main flexible wiringsubstrate 40 is connected to the liquid crystal display panel.

For example, a black frame 210 is formed by printing in the periphery ofthe front window 200. The area surrounded by the black frame 210 is adisplay area 220. In FIG. 11, the touch-panel flexible wiring substrate50 has a touch-panel electronic component group 51 and a touch-panelcontrol IC 52. Further, the touch-panel flexible wiring substrate 50also has a terminal portion 53 to connect to the outside. The mainflexible wiring substrate 40 has an LCD electronic component group 41 todrive the liquid crystal display panel. Further, the main flexiblewiring substrate 40 also has a terminal portion 44 to connect to theoutside.

FIG. 12 is a top view of the liquid crystal display panel used in FIG.11. In FIG. 12, the liquid crystal display panel including a TFTsubstrate 10 and a color filter substrate 20 is placed on a resin mold60. An upper polarization plate 21 is attached to the top surface of thecolor filter substrate 20.

The TFT substrate 10 is made larger than the color filter substrate 20.A terminal area is formed in a portion of the TFT substrate 10 extendingbeyond the color filter substrate 20. A liquid crystal driver IC 30 fordriving the liquid crystal display panel is provided in the terminalarea. Further, the main flexible wiring substrate 40 is attached to theterminal area. The LCD electronic component group 41 is mounted on themain flexible wiring substrate 40.

FIG. 13 is a top view of a touch panel 100 to be mounted on the liquiddisplay panel. The touch panel 100 includes a substrate and a wiringportion, as will be described below. The touch-panel flexible wiringsubstrate 50 is attached to the touch panel 100. The touch-panelflexible wiring substrate 50 has the touch-panel control IC 52 or thetouch-panel electronic component group 51. The touch-panel control IC 52or the touch-panel electronic component group 51 is mounted on thetouch-panel flexible wiring substrate 50, so that the touch panelmanufacture can determine whether the touch panel 100 is good or bad.

As described above, in the conventional type, the electronic componentsor the control IC is provided both in the main flexible wiring substrate40 and the touch-panel flexible wiring substrate 50. Mounting theelectronic components or the control IC on the flexible wiringsubstrates is a process that requires a lot of man-hours. As a result,the production cost of the liquid crystal display device increases. Inaddition, mounting the electronic components or the control IC on theflexible wiring substrates requires an increase in the size of eachflexible wiring substrate itself. As a result, the cost of the flexiblewiring substrate increases.

SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to avoid mounting theelectronic components and/or control IC on both the touch-panel flexiblewiring substrate 50 and the main flexible wiring substrate 40, in orderto reduce the production cost of the liquid crystal display device.

The present invention overcomes the above problem by the followingmeans.

(1) In a liquid crystal display device, a liquid crystal display panelincluding a TFT substrate and a color filter substrate, and a backlightare placed in a resin mold. A touch panel is attached to the liquidcrystal display panel. A front window is attached to the touch panel. Amain flexible wiring substrate is connected to the liquid crystaldisplay panel. A touch-panel flexible wiring substrate is connected tothe touch panel. The touch-panel flexible wiring substrate is connectedto the main flexible wiring substrate. The TFT substrate includes aliquid crystal driver IC. The main flexible wiring substrate includes anLCD electronic component group. In addition, the main flexible wiringsubstrate also includes a touch-panel control IC and a touch-panelelectronic component group in order to drive the touch panel.

(2) In the liquid crystal display device described in (1), the touchpanel is of a capacitance type.

(3) In the liquid crystal display device described in (1), a part of themain flexible wiring substrate branches to form a light emitting diodeflexible wiring substrate on which a light emitting diode is mounted.The light emitting diode flexible wiring substrate is folded behind theresin mold. The light emitting diode functions as a light source of thebacklight.

(4) In a liquid crystal display device, a liquid crystal display panelincluding a TFT substrate and a color filter substrate, and a backlightare placed in a resin mold. A touch panel is attached to the liquidcrystal display panel. A front window is attached to the touch panel. Amain flexible wiring substrate is connected to the liquid crystaldisplay panel. A touch-panel flexible wiring substrate is connected tothe touch panel. The touch-panel flexible wiring substrate is connectedto the main flexible wiring substrate. The TFT substrate includes aliquid crystal driver IC and a touch-panel control IC. The main flexiblewiring substrate includes an LCD electronic component group and atouch-panel electronic component group.

(5) In the liquid crystal display device described in (4), the touchpanel is of a capacitance type.

(6) In the liquid crystal display device described in (4), a part of themain flexible wiring substrate branches to form a light emitting diodeflexible wiring substrate on which a light emitting diode is mounted.The light emitting diode flexible wiring substrate is folded behind theresin mold. The light emitting diode functions as a light source of thebacklight.

According to the present invention, the touch-panel control IC and thetouch-panel electronic component group are removed from the touch-panelflexible wiring substrate. Thus, it is possible to reduce the cost formounting the electronic components and the like on the touch-panelflexible wiring substrate. At the same time the size of the touch-panelflexible wiring substrate can be reduced, resulting in a reduction inthe cost of the touch-panel flexible wiring substrate.

According to another aspect of the present invention, the touch-panelcontrol IC is attached to the liquid crystal display panel. This makesit possible to reduce the size of the touch-panel flexible wiringsubstrate, and to prevent an increase in the size of the main flexiblewiring substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a liquid crystal display device according to afirst embodiment;

FIG. 2 is a top view of a liquid crystal display panel according to thefirst embodiment;

FIG. 3 is a top view of a touch panel;

FIG. 4 is a top view of a front window;

FIG. 5 is a cross-sectional view of the touch panel;

FIG. 6 is a cross-sectional view of the liquid crystal display deviceaccording to the first embodiment;

FIG. 7 is a top view of the liquid crystal display device according to asecond embodiment;

FIG. 8 is top view of the liquid crystal display panel according to thesecond embodiment;

FIG. 9 is a perspective view of a main flexible wiring substrateaccording to a third embodiment;

FIG. 10 is a cross-sectional view of the liquid crystal display deviceaccording to a third embodiment;

FIG. 11 is a top view of a conventional liquid crystal display device;

FIG. 12 is a top view of a conventional liquid crystal display panel;and

FIG. 13 is a top view of a conventional touch panel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be disclosed in detail according to thepreferred embodiments.

First Embodiment

FIG. 1 is a top view of a liquid crystal display device according to afirst embodiment of the present invention. FIG. 2 is a top view of aliquid crystal display panel hidden behind a front window 200 of FIG. 1.FIG. 3 is a top view of a touch panel 100 hidden behind the front window200 of FIG. 1. FIG. 4 is a top view of the front window 200. FIG. 1schematically illustrates the manner in which FIGS. 2 to 4 are assembledtogether.

In FIG. 1, the front window 200 is provided on the top surface of theliquid crystal display device. The touch panel 100 and the liquidcrystal display panel are actually present under the front window 200.However, the touch panel 100 and the liquid crystal display panel arehidden behind the front window 200, and are not shown in the figure. InFIG. 1, a touch-panel flexible wiring substrate 50 and a main flexiblewiring substrate 40 appear from the short side below the front window200. When the liquid crystal display device is assembled into a mobilephone or another electronic device, the main flexible wiring substrate40 and the touch-panel flexible wiring substrate 50 are folded behind aresin mold which will be described below.

As shown in FIG. 1, the control IC or the electronic component group isnot provided in the touch-panel flexible wiring substrate 50. For thisreason, the size of the touch-panel flexible substrate 50 can bereduced. Meanwhile in the main flexible wiring substrate 40, not only anLCD electronic component group 41 but also a touch-panel electroniccomponent group 51 and a touch-panel control IC 52 are provided. Aterminal portion 53 of the touch-panel flexible wiring substrate 50 isconnected to a connecting portion 43 of the main flexible wiringsubstrate 40.

FIG. 2 is a top view of the liquid crystal display panel. In FIG. 2, acolor filter substrate 20 is placed above a TFT substrate 10. A liquidcrystal layer, not shown, is interposed between the TFT substrate 10 andthe color filter substrate 20. The TFT substrate 10 and the color filtersubstrate 20 are bonded together by a sealing material, not shown,formed in the frame portion of the liquid crystal display panel. The TFTsubstrate 10 is made larger than the color filter substrate 20. Aterminal area is formed in the portion of the TFT substrate 10 extendingbeyond the color filter substrate 20. Power, image signals, scansignals, and the like, are supplied to the liquid crystal display panelfrom the terminal area of the TFT substrate 10.

A liquid crystal IC driver 30 is provided in the terminal area to drivescan lines, image signal lines, and the like. The liquid crystal ICdriver 30 has a scan line driving circuit and an image signal linedriving circuit. Then, scan signals and image signals are supplied tothe liquid crystal IC driver 30 through the main flexible wiringsubstrate 40 connected to the terminal area.

The upper polarization plate 21 is attached to the top of the colorfilter substrate 20. The liquid crystal can control only polarizedlight, so that a lower polarization plate is attached to the bottom ofthe TFT substrate 10 in order to polarize the light from the backlightinto linearly polarized light. The linearly polarized light is modulatedby the liquid crystal layer. The transmittance is changed for eachpixel, and thus an image is formed. Then, the image is polarized(analyzed) again by the upper polarization plate 21 and is visible tothe human eyes. The whole liquid crystal display panel is placed in aframe-like resin mold 60. The backlight described below is placed on thelower side of the liquid crystal display panel, which are placed in theresin mold 60.

As shown in FIG. 2, the main flexible wiring substrate 40 includes thetouch-panel control IC 52 and the touch-panel electronic component group51, in addition to the LCD electronic component group 41. The terminalportion 43 of the main flexible wiring substrate 40 is also suppliedwith a control signal and the like for the touch panel. The mainflexible wiring substrate 40 is connected to the touch-panel flexiblewiring substrate 50 through the connecting portion 43. The signal forcontrolling the touch panel is transmitted from the main flexible wiringsubstrate 40.

In this embodiment, the number of electronic components mounted on themain flexible wiring substrate 40 is greater than that in theconventional example. However, the electronic components are not mountedon the touch-panel flexible wiring substrate 50. The number of flexiblewiring substrates on which the electronic components are mounted hasgreater effect on the cost for mounting the electronic components, thanthe number of electronic components mounted on the flexible wiringsubstrate. For this reason, all the electronic components are mounted onthe main flexible wiring substrate 40, as in the present invention, toreduce the production cost of the liquid crystal display device. On theback side of the main flexible wiring substrate 40, there is provided alight emitting diode used for the backlight described below.

FIG. 3 is a top view of the touch panel 100 attached to the liquidcrystal display panel described in FIG. 2. The touch panel 100 is madeslightly larger than the color filter substrate 20 of the liquid crystaldisplay panel. In FIG. 3, the touch-panel flexible wiring substrate 50is attached to an end of the touch panel 100 to supply power and signalsto the touch panel 100.

In the touch-panel flexible wiring substrate 50, the electroniccomponent group and/or touch-panel control IC are not provided, but onlylines are formed. For this reason, the size of the touch-panel flexiblewiring substrate 50 is small. Further, the production cost of thetouch-panel flexible wiring substrate 50 can be significantly reduceddue to the absence of the mounting operation of the electroniccomponents and the like. The touch-panel flexible wiring substrate 50 isconnected to the main flexible wiring substrate 40 through the terminalportion 53.

The touch panel 100 shown in FIG. 3 is the capacitance-type touch panel100. FIG. 5 is a schematic cross-sectional view of the capacitance-typetouch panel 100. In FIG. 5, lower lines 102 are formed on a touch panelsubstrate 101. An insulating layer 103 is formed on the lower lines 102.Upper lines 104 are formed on the insulating layer 103. Then, aprotective layer 105 is formed to cover the upper lines 104.

In general, the touch panel substrate 101 is formed from glass. However,a plastic substrate may also be used if it is transparent and cansustain anneal temperatures for ITO, and the like. Examples of thetransparent resin include acryl and polycarbonate.

The lower lines 102 are formed on the surface of the touch panelsubstrate 101. The lower lines 102 are formed from ITO which is atransparent conductive film. The ITO is deposited by sputtering, and ispatterned into strips which extend in the x direction and are arrangedin the y direction, namely, in the direction perpendicular to the paper.

The insulating layer 103 is formed from SiO₂ or SiN film to cover thelower lines 102. The upper lines 104 are formed on the insulating layer103. The upper lines 104 are also formed from a transparent conductivefilm of ITO. The ITO is deposited by sputtering, and is patterned intostripes which extend in the y direction in FIG. 5, namely, in thedirection perpendicular to the paper, and are arranged in the xdirection.

In FIG. 5, the lower lines 102 and the upper lines 104 are arrangedperpendicular to each other. The lower lines 102 and the upper lines 104form the sides of squares, when seen from the top. It is also possibleto pattern the lower lines 102 and the upper lines 104 into stripsextending in an oblique direction to the profile of the touch panel 100.In such a case, the lower lines 102 and the upper lines 104 form thesides of rhombuses, when seen from the top.

The upper lines 104 are covered and protected by the protective layer105 formed from SiO₂ or SiN film. In this embodiment, the front window200 is placed on the touch panel 100. However, if there is no frontwindow 200, the touch panel 100 will be directly touched by a specialpen or finger. At this time, the protective layer 105 prevents the linesfrom being damaged.

When a special pen or finger touches an upper electrode through theprotective layer 105 and the front window 200, a capacitance is formedbetween the upper line 104 and the special pen or finger. This causes amovement of the charge generated between the upper and lower electrodes.Thus, the position can be detected.

In FIG. 5, the upper lines 104 are electrically connected to theterminal portion of the touch panel 100 through a through hole, notshown, formed in the insulating layer 103. In other words, the terminalof the touch panel 100 can supply signals and current both to the upperline 104 and the lower line 102. For this reason, one touch-panelflexible wiring substrate 50 is enough to be connected to the touchpanel 100.

The touch-panel flexible wiring substrate 50 is connected by ananisotropic conductive film 106 in the terminal area of the touch panel100. In the present invention, the touch-panel control IC and/ortouch-panel electronic component group are mounted on the main flexiblewiring substrate. Thus, in the terminal portion of the touch-panelflexible wiring substrate 50, solder may be used for connection toreduce the resistance of the terminal portion.

When the touch-panel manufacture ships the touch panel 100, it isnecessary to test the operation of the touch panel 100. In theconventional technology, the touch panel 100 has the touch-panelflexible wiring substrate 50 on which the touch-panel control IC and thetouch-panel electronic component group are mounted. Thus, it is possibleto test the touch panel by itself. However, the touch-panel flexiblewiring substrate 50 used in the present invention has only the lines, sothat the touch panel 100 may not be tested alone.

For this reason, the touch panel test is performed by combining theliquid crystal display panel on which the main flexible wiring substrate40 is mounted. Another method is to incorporate the function of thetouch-panel control IC and the touch-panel electronic component groupmounted on the main flexible wiring substrate 40, to a touch panel testdevice.

The touch panel 100 is attached to the color filter substrate 20 of theliquid crystal display panel by an adhesive material. The adhesivematerial is a thermoplastic resin, for example, of acrylic transparentadhesive. This is because when defects such as air bubbles or foreignmaterials are found after completion of the product, the defectiveportion is repaired by detaching the front window 200, the touch panel100, and the liquid crystal display panel from each other.

FIG. 4 is a top view of the front window 200 attached to the touch panel100. In general, the front window 200 is formed from glass with athickness of about 0.5 mm. Plastic such as acrylic resin andpolycarbonate resin can also be used as the material of the front window200.

The overall size of the front window 200 is larger than the liquidcrystal display panel and the resin mold 60, protecting the whole of theliquid crystal display panel and the like. A black frame 210 is formedby printing in the periphery of the front window 200. The electroniccomponents, the resin mold and the like, are present under the blackframe 210. A logo or a mark is formed by printing in the frame 210 ifnecessary. The area surrounded by the black frame 210 is a display area220.

The front window 200 is attached to the touch panel 100 by an adhesivematerial. The adhesive material is preferably a thermoplastictransparent acrylic resin or other thermoplastic resin. This is becausewhen defects such as air bubbles and foreign substances are found aftercompletion of the product, the defective portion is repaired bydetaching the front window 200, the touch panel 100, and the liquidcrystal display panel from each other.

FIG. 6 is a cross-sectional view of the liquid crystal display deviceshown in FIG. 1. In FIG. 6, however, the LCD electronic component group41, the touch-panel electronic component group 51, the touch-panelcontrol IC 52 and the like are provided under the front window 200. Thetouch panel 100 is bonded to the upper polarization plate 21 bonded tothe color filter substrate 20 by a first adhesive material 110. Theconfiguration of the touch panel 100 is as described above. The mainflexible wiring substrate 40 shown in FIG. 1 is folded behind the resinmold 60.

The front window 200 is attached on the touch panel 100 by a secondadhesive material 120. The overall size of the front window 200 is largeenough to cover both the touch-panel flexible wiring substrate 50 andthe main flexible wiring substrate 40. In this embodiment, a transparentacrylic adhesive is used for the first adhesive material 110 and thesecond adhesive material 120.

In FIG. 6, the liquid crystal display panel is provided on the resinmold 60. In FIG. 6, the lower polarization plate 11 is placed in theresin mold 60, and a backlight is provided in the back of the lowerpolarization plate 11. The backlight has the following configuration.

A light guide panel 62 is disposed so that the end thereof faces thelight emitting diode 70. The role of the light guide panel 62 is todirect the light emitted from the light emitting diode 70 and enteringfrom the side surface, towards the liquid crystal display panel. Thesize of the light emitting diode 70 is large. Thus, the thickness of thewhole liquid crystal display device is reduced by increasing thethickness of the portion of the light guide panel 62 facing the lightemitting diode 70, and by reducing the thickness of the portion thereofon which an optical sheet described below is placed.

In FIG. 6, a reflective sheet 61 is provided under the light guide panel62. This is in order to reflect and direct the light downward from thelight guide panel 62, to the side of the liquid crystal display panel.On the upper side of the light guide panel 62, there is provided anoptical sheet group 63 including a lower diffusion sheet, a lower prismsheet, an upper prism sheet, and an upper diffusion sheet. The prismsheets are used for increasing the use efficiency of light from thebacklight. The diffusion sheets are used for preventing the occurrenceof uneven brightness and moiré.

In FIG. 6, the optical sheet group 63 is placed on the light guide panel62. For example, the distance between the upper diffusion sheet, whichis the top of the optical sheet group 63, and the lower polarizationplate 11 of the liquid crystal display panel is about 50 μm. This makesit possible to prevent scratches caused by friction between the lowerpolarization plate 11 and the upper diffusion sheet.

The touch-panel flexible wiring substrate 50 is connected to the touchpanel 100. The touch-panel control IC and/or touch-panel electroniccomponent group are not mounted on the touch-panel flexible wiringsubstrate 50 in which only lines are formed. The touch-panel flexiblewiring substrate 50 is connected to the main flexible wiring substrateconnected to the liquid crystal display panel.

The liquid crystal driver IC 30 is mounted on the liquid crystal displaypanel. The main flexible wiring substrate 40 is folded behind thebacklight. The light emitting diode 70 is mounted on the main flexiblewiring substrate 40, and functions as a light source of the backlight.When the main flexible wiring substrate 40 is folded behind thebacklight, the light emitting diode 70 is placed in a concave formed inthe resin mold 60. Then, as shown in FIG. 6, the light emitting diode 70is disposed facing the end of the light guide panel 62 to function as alight source of the backlight. In this embodiment, a white lightemitting diode is used as the light emitting diode 70.

The main flexible wiring substrate 40 has the LCD electronic componentgroup 41 to control the liquid crystal display panel. In addition, themain flexible wiring substrate 40 also has the touch-panel control IC 52and/or the touch-panel electronic component group 51 to control thetouch panel. The touch panel 100 is controlled by the touch-panelcontrol IC 52 and the like provided in the main flexible wiringsubstrate 40.

In this embodiment, the touch-panel control IC and/or touch-panelelectronic component group are not mounted on the touch-panel flexiblewiring substrate 50. Thus, it is possible to reduce the man-hours formounting such components on the touch-panel flexible wiring substrate50. Further, it is also possible to reduce the size of the touch-panelflexible wiring substrate 50. On the other hand, the touch-panel controlIC 52 and the touch-panel electronic component group 51 are mounted onthe main flexible wiring substrate 40. However, the number of additionalman-hours for mounting these components is very small. As a result, theproduction cost of the liquid crystal display device according to thisembodiment can be substantially reduced.

Second Embodiment

FIG. 7 is a top view of the liquid crystal display device according to asecond embodiment of the present invention. FIG. 7 is different fromFIG. 1, which is a top view of the liquid crystal display device of thefirst embodiment, in the main flexible wiring substrate 40 connected tothe liquid crystal display panel. In FIG. 7, the touch-panel flexiblewiring substrate 50 is connected to the touch panel 100. The touch-panelcontrol IC and/or touch-panel electronic component group are not mountedon the touch-panel flexible wiring substrate 50 in which only lines areformed. The second embodiment is the same as the first embodiment inthis point. Also, the touch panel 100 and the front window 200 used inthe second embodiment are the same as those described in the firstembodiment.

In FIG. 7, the terminal portion 53 of the touch-panel flexible wiringsubstrate 50 is connected to the connecting portion 43 of the mainflexible wiring substrate 40. Here, the touch-panel electronic componentgroup 51 is mounted on the main flexible wiring substrate 40, inaddition to the LCD electronic component group 41. However, thetouch-panel control IC 52 is not mounted on the main flexible wiringsubstrate 40. The second embodiment is different from the firstembodiment in this point.

FIG. 8 is a top view of the liquid crystal display panel used in theliquid crystal display device of FIG. 7. In FIG. 8, the liquid crystaldriver IC 30 and the touch-panel control IC 52 are provided in theterminal area of the TFT substrate 10. The liquid crystal driver IC 30and the touch-panel control IC 52 are directly mounted on the TFTsubstrate 10 in the chip state.

In this embodiment, the touch panel 100 is controlled by the touch-panelcontrol IC 52 mounted on the liquid crystal display panel, through themain flexible wiring substrate 40 and through the touch-panel flexiblewiring substrate 50. However, the touch-panel electronic component group51 is mounted on the main flexible wiring substrate 40. Thus, the touchpanel 100 is controlled in cooperation with the touch-panel electroniccomponent group 51 of the main flexible wiring substrate 40, and thetouch-panel control IC 52 on the liquid crystal display panel.

In this case, in the TFT substrate 10, when the line resistance is largebetween the terminal portion of the main flexible wiring substrate 40and the touch-panel control IC 52, the response speed of the touch panel100 is delayed or other problem occurs. The terminal portion of the mainflexible wiring substrate 40 and the touch-panel control IC 52 can bewired simultaneously with the formation of the image signal lines of theTFT substrate 10. The image signal lines are formed from Al or Al alloy,so that the line resistance can be reduced. Further, except in theterminal portion or the portion connecting to the touch-panel control IC52, the lines can be covered by an inorganic passivation film, anorganic passivation film and the like. In this way, the reliability ofthe lines can be ensured.

In this embodiment, the touch-panel control IC 52 can be mounted on theTFT substrate 10 in the chip state. Thus, the area occupied by thetouch-panel control IC 52 can be made smaller than the case in which thetouch-panel control IC 52 is mounted on the flexible wiring substrate.Further, in this embodiment, the touch-panel control IC 52 is mounted onthe liquid crystal display panel. Thus, the size of the main flexiblewiring substrate 40 can be made smaller than in the first embodiment.Consequently, according to this embodiment, it is possible to reduce thesize of the liquid crystal display device as a whole. Further, theelectric components and the like are not mounted on the touch-panelflexible wiring substrate 50. As a result, the production cost of theliquid crystal display device can be reduced, which is the same as inthe first embodiment.

Third Embodiment

FIG. 9 is a perspective view of the main flexible wiring substrate 40according to a third embodiment of the present invention. The top viewof the liquid crystal display device in the third embodiment is the sameas FIG. 1 in the first embodiment. The top view of the liquid crystaldisplay panel is also the same as FIG. 2 in the first embodiment.Further, the touch panel 100 and the front window 200 used in the thirdembodiment are the same as those described in the first embodiment.

In FIG. 9, a part of the main flexible wiring substrate 40 branches toform a light emitting diode flexible wiring substrate 45. The lightemitting diode flexible wiring substrate 45 is folded behind the resinmold 60. The light emitting diode 70 of the light emitting diodeflexible wiring substrate 45 is disposed on a side surface of the lightguide panel of the backlight not shown. In the first or secondembodiment, all of the main flexible wiring substrate 40 is foldedbehind the resin mold 60. In the third embodiment, however, only thelight emitting diode flexible wiring substrate 45 branching from themain flexible wiring substrate is folded behind the resin mold 60.

The third embodiment is the same as the first embodiment in that themain flexible wiring substrate 40 has the LCD electronic component group41, as well as the touch-panel control IC 52 or the touch-panelelectronic component group 51. The touch-panel control IC 52 can also beprovided in the terminal area of the TFT substrate 10 as described inthe second embodiment, instead of being mounted on the main flexiblewiring substrate 40.

FIG. 10 is a cross-sectional view of the liquid crystal display deviceaccording to the third embodiment. FIG. 10 is the same as FIG. 6 of thefirst embodiment except for the main flexible wiring substrate 40. Inother words, the touch-pane control IC 52 and the touch-panel electroniccomponent group 51 are mounted on the main flexible wiring substrate 40to control the touch panel 100. In FIG. 10, the light emitting diodeflexible wiring substrate 45 branching from the main flexible wiringsubstrate 40 is folded behind the resin mold 60. Then, the lightemitting diode 70 of the light emitting diode flexible wiring substrate45 is provided on the side surface of the light guide panel 62.

Also in this embodiment, it is possible to obtain the same effect as inthe first embodiment. In other words, the present invention can beapplied in the use of different types of the main flexible wiringsubstrate 40. Further, in FIGS. 9, 10 and other figures, the touch-panelcontrol IC 52 and the touch-panel electronic component group 51 aremounted on the main flexible wiring substrate 40. As described in thesecond embodiment, however, the touch-panel control IC 52 can beprovided in the terminal area of the TFT substrate 10 in FIG. 9 or 10,instead of being mounted on the main flexible wiring substrate 40.

What is claimed is:
 1. A display device comprising: a display panel, anda touch panel attached to the display panel; wherein a main flexiblewiring substrate is connected to the display panel, wherein atouch-panel flexible wiring substrate is connected to the touch panel,said touch-panel flexible wiring substrate being an independentcomponent from the touch panel, wherein a terminal portion of thetouch-panel flexible wiring substrate is directly connected to aconnecting portion of the main flexible wiring substrate, wherein thedisplay panel includes a display panel driver IC, wherein the mainflexible wiring substrate includes a display panel electronic componentgroup, wherein the main flexible wiring substrate further includes atouch-panel control IC and a touch-panel electronic component group todrive the touch panel, wherein no electronic components, including thetouch-panel control IC and the touch-panel electronic group to drive thetouch-panel, are mounted on the touch-panel flexible wiring substrate,wherein, in a plan view, the touch-panel flexible wiring substrate andthe main flexible wiring substrate overlap, wherein the terminal portionof the touch-panel flexible wiring substrate is located between thetouch-panel electronic component group and the display panel electroniccomponent group, wherein a width of the terminal portion of thetouch-panel flexible wiring substrate is narrower than a distancebetween the touch-panel electronic component group and the display panelelectronic component group, wherein a width of connecting portion of thetouch-panel flexible wiring substrate is wider than the distance betweenthe touch-panel electronic component group and the display panelelectronic component group.
 2. The display device according to claim 1,wherein the touch panel is of a capacitance type and the display deviceis configured for mobile electronic devices.
 3. The display deviceaccording to claim 1, the touch-panel flexible wiring substrate includesonly wires.
 4. A display device comprising: a display panel, and a touchpanel attached to the display panel; wherein a main flexible wiringsubstrate is connected to the display panel, wherein a touch-panelflexible wiring substrate is connected to the touch panel, saidtouch-panel flexible wiring substrate being an independent componentfrom the touch panel, wherein a terminal portion of the touch-panelflexible wiring substrate is directly connected to a connecting portionof the main flexible wiring substrate, wherein the display panelincludes a display panel driver IC and a touch panel control IC, whereinthe main flexible wiring substrate includes a display panel electroniccomponent group and a touch panel electronic component group, wherein noelectronic components, including the touch-panel control IC and thetouch-panel electronic group to drive the touch-panel, are mounted onthe touch-panel flexible wiring substrate, wherein, in a plan view, thetouch-panel flexible wiring substrate and the main flexible wiringsubstrate overlap, wherein a width of connecting portion of thetouch-panel flexible wiring substrate is wider than the distance betweenthe touch-panel electronic component group and the display panelelectronic component group.
 5. The display device according to claim 4,wherein the touch panel is of a capacitance type and the display deviceis configured for mobile electronic devices.
 6. The display deviceaccording to claim 4, the touch-panel flexible wiring substrate includesonly wires.